Hi
I have just ported my code that was working without a RTOS to CMSIS RTOS and its loaded onto my cortex m3 arm and my code gets through by board initialization but as I get a stack overflow when the RTOS tries to start the first task.
I have configured 0x8200 bytes for my stack, 7 tasks, 2000 bytes for the default thread and 800 bytes for the other 6 threads. The thread viewer shows two additional threads, timer and idle. My stack is located in the esram and is using all available bytes there.
I really do not have any idea what I have done wrong in allocating memory for the stack or in configuring the RTOS. I feel I missed something in the setup.
I was thinking about backing off the 7 threads and just try to start 1 and see if that overflows.
Is it possible to relocate my stack to my DDR memory space at 0xA0000000 so I can make the available stack size bigger? I don't know if throwing more memory at it will really solve this problem.
Does anyone have any ideas about what might be wrong or how I might go about debugging this overflow issue?
A test I just ran was to create only 1 task and give it 3000 bytes which is way over what it needs and I still got a stack overflow. So there has to be something else going on with the RTOS and thread stacks.
Its like the RTOS does not know anything about the stack. It seems to think its zero size I guess.
I stopped the main/default thread that initializes the system and creates the thread right when it is going to osDelay() which will give up control to the next thread. I looked at the system and thread viewer and the task that will run next is only using 2% of the stack. The osTimerThread (RTOS thread) is using 40%. this is not any of the my threads.
I have a break point at the start of the next thread but it gets a stack overflow before even getting to its first instruction.
I don't see any reason for the that thread's stack to overflow when it has not even been able to run yet. That is what I don't understand.
It is possible that something else corrupts stack memory making the OS think it overflows...?
I started to debug the createTask function and found that it calls rt_alloc_mem (os_stack_mem, thread_def->size) and during the allocation of memory I get a hard fault when it tries to "insert list element" by writing to a mem pool pointer p.
/* Insert new list element into the memory list */ p = (MEMP *)(((U32)p_new) + sizeof(MEMP));
this is the store instruction that faults: STR r1,[r0,#0x00] r1 = 0x40093b2c r0 - 0xA0049c18 where r1 = p* r0 = p_new* MEMP is a memory pool data structure
This memory pool is os_stack_size = 0xE98 and created during KernelInitialize() by a call to rt_init_mem() and osTimerThread (stacksize = 0xC8)is created ok and taking some memory from this stack memory pool.
So at least one thread was created and there is a lot of stack memory left for my thread.
when createThread is called with my thread it goes through the same processing but throws a hard fault at the line above. I cannot see any of the variables so I do not know what is causing this.
The RTOS is not compiled debug I assume.
This does not make sense to me right now. Why a hard fault?
Good thought but I think that is not a problem. It appears this "stack memory pool" that is created by rt_init_mem from the kernelInitialize() call allocates it at memory address (os_stack_mem) is at 0xA0048b48
Nothing else is running during initialization so there cannot be any other thread of anything to step on the stack memory.
os_stack_mem 0xa0049b48 Data 3736 size rtx_conf_cm.o(.bss)
If you have any other ideas, please let me know
Here is some additional information I found. I did not have the "if (!osKernelRunning)" when I ran. Apparently I was calling osKernelInitialize twice. It is called automatically before my main task runs which I did not realize.
I can successfully create my timer task.
So that was my problem it seems. Don't call KernelInitialize twice